"The fact of the matter is that they're in 2018 midterm election war footing," he said. "The president maybe could have done some things differently -- could of shortened it, got a bigger and more unified theme. But in the end, I don't know if they would have even stood up then."

Christie added: "That was a pretty glum looking group of Democrats all through the evening."

The former governor gave his take on ABC News, where he was hired as a contributor because he's close to the president and the players inside the White House.

What did he think of the president's speech?

"(It was a) traditional State of the Union," Christie said, adding, "I thought it was too long."

He focused on the Democrats after nearly a half dozen ABC News reporters and analysts reacted to Trump's speech, with some saying they thought he would make a greater effort to unite a divided nation.

Christie's quick take concluded his first day on the job for the network. His State of the Union analysis came hours after his debut appearance earlier in the morning -- two weeks to the day after he left office.

Earlier, Christie talked briefly about Trump's upcoming speech and the federal probe led by special counsel Robert Mueller investigating possible coordination between the Kremlin and the Trump presidential campaign.

"The one thing I can tell you for sure, and one of the things I loved about being a prosecutor, was only I knew what I knew," Christie told ABC's George Stephanopoulos .

"Only Bob Mueller really knows what he knows, and we won't know it for a while," he said, "So everybody who speculates about this stuff, George -- they're throwing darts at the wall with a blindfold on. Bob Mueller knows what's going on."